early 15c., "damage, injury," from Old French lesion "hurt, offense, wrong, injury, wound" (12c.), from Latin laesionem (nominative laesio) "a hurting, injuring, personal attack," noun of action from past participle stem of laedere "to strike, hurt, damage," a word of unknown origin with no certain cognates. Originally in English with reference to any sort of hurt, whether physical or not.